1. Field of the Invention
This invention relates to a so-called pressure sensitive transferring member such as a pressure sensitive ink ribbon and the like, and more particularly, to a correctable pressure sensitive transferring member or ink ribbon having improved pressure sensitive property and correction property due to an improved ink layer.
2. Description of the Prior Art
Correctable ink ribbons have been developed for enabling the correction of mistakenly typewritten letters. Such correctable ink ribbons are usually constituted of a pressure sensitive transferable ink layer formed on a film substrate. In a typewriter using such a correctable ink ribbon. A cohesive ribbon or tape for correction difficult from the ink ribbon is superposed on a mistakenly recorded transferred ink image, and typewriting is effected again to remove the mistakenly recorded transferred ink image from a recording medium such as typewriting paper. A correct ink image is, then, typewritten on the removed portion by using the ink ribbon again resulting in correction of record.
The correctable ink ribbon in involved in transferring and, if necessary, correcting the transferred image and transferring again, and the like.
Therefore, the correctable ink ribbon should have a characteristic that the mistakenly recorded transferred image can be easily removed by a cohesive ribbon or tape for correction, and furthermore, have the following characteristics:
(1) The ink layer in the form of an image is completely peeled off from the substrate by an image forming pressure such as typewriting pressure upon transferring, and the form of image is completely transferred to the recording medium (transferring property);
(2) The mistakenly recorded transferred image can be easily removed by a cohesive ribbon or tape for correction and, upon peeling off the transferred image from the recording medium for correcting, running of oil and the like which becomes a trace of the transferred image are not left on the recording medium (correction property);
(3) During storage, the ink layer does not fall off from the substrate (durability of the ink layer) and the like.
In such an ink ribbon, the transferring ink constituting the ink layer formed on the film substrate may be usually composed of synthetic resin binder material, oily material as a plasticizer for the binder material, coloring agent and the like.
As the plasticizer in the transferring ink, there may be generally used a mineral oil such as liquid paraffin, spindle oil, motor and the like, or a fatty acid ester such as butyl stearate and the like.
Such a plasticizer is added to the ink so as to mainly impart softness to the ink layer and impart a pressure sensitive transferring property to the ink layer. Therefore, the plasticizer should have a function to weaken the resin binder material and a stronger affinity to the recording medium than to the film substrate so as to enable a good transfer, and the affinity should be such that running oil is not left on the recording medium upon correction.
However, in the case where a minimeral oil such as liquid paraffin and the like which are widely used is employed as a plasticizer, there occurs poor transferring such as an incomplete transferring to the recording medium upon transferring at a low temperature, for example, 10.degree. C. and further, running of oil resulting in a trace of a transferred image is left on the recording medium when the transferred ink image is peeled off from the recording medium upon correction.
In addition, where a fatty acid ester such as butyl stearate and the like is used as a plasticizer, running of oil resulting in a trace of a transferred image is disadvantageously left on the recording medium when the transferred image is peeled off from the recording medium upon correction.